How a medical breakthrough has saved the lives of many New Zealanders

While the rate of stomach cancer has been slowly declining for Pākehā and Asian populations, the overall rate among Māori and Pasifika is three times what it should be based on population size.

One of the reasons is Māori are far more likely to carry an inherited gene called CDH1 - and knowing your whakapapa could save your life. 

For the McLeod whānau in Tauranga, they're celebrating 25 years since they made a medical breakthrough that has saved the lives of many people.

Maybelle McLeod visits one urupa often. Three decades ago, her family was dying of hereditary diffuse gastric cancer in terrifying numbers.

There was talk the whānau was cursed because they sold the hill behind their papakainga, but McLeod, who is a medical professional, didn't buy it.

"Too many people are dying from one family," she told The Hui.

Seeking answers, McLeod contacted Professor Parry Guilford, a cancer geneticist from the University of Otago.

When he first met the family, Prof Guilford said he knew it was genetic.

"We'd seen enough of the family tree to know it was genetic. We didn't know what the gene was, of course, and we weren't sure. We wouldn't know how to find it. But we knew it was genetic," he told The Hui.

McLeod and her team got to work tracing the whānau's whakapapa and took samples of everyone they could find.

"A lot of people who knew a bit about our whakapapa genealogy have passed away, so we had to rely on books that had been left behind by both by the family, by the whānau, and work our way this way downwards from there."

Prof Guilford had an incredible stroke of luck. The human body carries 20,000 genomes, but it was only the fifth gene he tested that provided the answer.

"Yeah, we got really lucky. And I mean, I got really lucky. So we could have been still looking now," he said.

Maybelle McLeod.
Maybelle McLeod. Photo credit: The Hui

The McLeod whānau carries what is called the CDH1 gene, which causes a mutation that can lead to diffuse gastric cancer.

For the past 25 years, the McLeod whānau have been able to stay one step ahead of the gene. They built a clinic on their papakainga and every member of the family is tested. If they have CDH1, they can have their stomachs removed as a preventative measure.

One of them was singer Stan Walker - his aunt's intuition saved his life.

McLeod said she's glad that people in her whānau don't have to die anymore. And now, the CDH1 gene has been traced in families all over the world.

Here in New Zealand, 25 known families carry the gene and most of them are Māori. Dr Karyn Paringatai is not related to the McLeods, but she found out she carried the gene more than a decade ago and had her stomach removed.

"One hundred percent, they [the McLeod whānau] saved my life," she said.

Dr Paringatai now researches the importance of whakapapa and genetics. Her work emphasises the potentially lifesaving benefits of reconnecting with your whānau.

Her father was raised in Horoera, a small rural Māori community in the East Cape. In 1968, when he was 16 years old, he left Horoera for Invercargill for seasonal employment at the freezing works. He intended to return to the East Coast during the off-season, but he never did. 

That meant Dr Paringatai was disconnected from her whānau. It was only when she went back to the East Coast later in life that she found out she could be a carrier of the CDH1 gene.

"It hadn't really hit, this idea of whānau and whakapapa and what it meant. And then all of a sudden I'm faced with this genetic mutation that is throughout my whakapapa and I think that was where all my struggle was, not the gene itself and what that means, but just now being part of something bigger than just myself," she said.

Dr Paringatai encourages people to dig into their whakapapa and have conversations about medical histories. She also wants all Māori who have had a family member die of diffuse gastric cancer to seek answers - which could be found in the CDH1 gene.

Dr Paringatai said the medical community in Aotearoa doesn't know enough about this gene.

"Here in Tauranga, it's great because they have established this really good system within their whanau … But the rest of the country? Not at all," she said.

She also believes there are other whānau out there who have this gene but don't know about it.

Twenty-five years on since the CDH1 discovery, many people are alive because of this medical breakthrough between the McLeod whānau and Prof Guilford. Now the message is clear to other whānau - understand your whakapapa to protect your future.

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Made with support from Te Māngai Pāho and the Public Interest Journalism Fund.